Try to google "Studeriotes" and see if the results you get look similar to the coral they are selling. If it is, then it is a nonphotosynthetic soft coral. One of the easier nonphotos to keep, but you still need to make sure you offer it food often- preferably every day. Place it lower in the tank to discourage algae from overgrowing it, and provide moderate to strong water flow.
If thats NOT it, then Ive no clue. If it is truely a "Black Coral" then avoid it- they simply dont live in captivity (and to the best of my knowledge, are illegal to collect, though I could easily be wrong on that one).